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Welcome to the newest iteration of the Ecosystem Context for Stock Advice product for north black sea bass. You are looking at an intermediate draft that still needs some work. Check out github.com/noaa-edab/ecsa for more information on the build process that moves raw data -> stock-name_draft.rmd/Google Doc template -> stock-name.rmd/.html/.pdf final series of documents.

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Introduction

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This report provides contextual ecosystem information for north black sea bass (Centropristis striata) on the Northeast U.S. Continental Shelf. Data extractions for spring and fall are confined to the black sea bass stock area based on respective survey strata sets. The information is intended to span a range of potential factors affecting the productivity and distribution of black sea bass, including: surface and bottom temperature and salinity, chlorophyll concentrations, indices of habitat, diet composition, and abundance of key zooplankton prey of larval black sea bass. These factors can be used to qualitatively inform the interpretation of population status and/or quantitatively to improve model responsiveness to ecosystem factors. The range and complexity of ecosystem data makes it unlikely to find the most relevant and comprehensive factor variables with a first evaluation; this process will require an iterative approach of evaluation and feedback. Additional indices can be included to address the needs of the working group.

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Summary

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Stock area

Strata map for black sea bass (*Centropristis striata*) on the NE shelf

Strata map for black sea bass (Centropristis striata) on the NE shelf

A note on figures

Unless otherwise noted, time series in this document are represented by dark blue lines. Estimates of linear trends and regime shifts are included on plots when found to be significant (p < 0.05), and are shown by light blue and green lines respectively. Trend strengths and confidence intervals are also included in plot titles when trends are present. Trends were modeled using a GLS model selection approach [see @hardison2019 for details].

Last updated on July 24 2019.

Temperature

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An optimal interpolation procedure was used to estimate NE Shelf surface and bottom temperatures for two seasonal time frames (see #methodstempsalin). The temperature estimates were standardized to April 3 and October 11 for spring and fall over the period 1968-2018. Surface and bottom temperature within the black sea bass stock areas are shown below.

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Bottom Temperature

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Surface Temperature

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Salinity

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An optimal interpolation procedure was used to estimate NE Shelf surface and bottom salinity for two seasonal time frames (see #methodstempsalin). Though collected with temperature data, reliable instrumentation limits this time series to 1992-2018. The salinity estimates were standardized to April 3 and October 11 for spring and fall. Surface and bottom salinities within the black sea bass stock areas are shown below.

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Bottom Salinity

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Surface Salinity

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Chlorophyll

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Chlorophyll concentration in the stock area

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The concentration of chlorophyll was measured with a suite of satellite sensors and merged into a single dataset (see #methodschl). Chlorophyll concentrations in the spring and fall black sea bass stock areas are shown below.

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Zooplankton

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Copepod abundance

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Non-copepod zooplankton abundance

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Habitat and abundance

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Occurrence probability

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The probability of occurrence was estimated using random forest classification models (see #methodsocc). The mean annual probabilities were extracted for the spring and/or fall stock definition areas. These data provide an estimate of the potential use of the habitat associated with the stock definition.

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Habitat area

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Ecosystem area

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Stock

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Minimum Population Size

{{MinPopulationStart}} Estimates of the biomass for the minimum population size of monkfish was determined by re-stratifying the habitat each year depending on the distribution of occupancy habitat (see #methodsocc for details). The procedure provides eight population size estimates for each stock, by season, based on the use of three estimation options. The estimates are denoted by a three-letter code (Y/N|Y/N|Y/N) where the first position indicates whether data were interpolated over habitat strata. The second position indicates whether the trawl data applied to the estimate was limited to the stations made in the stock area only or if trawls from other areas were used as well. The third position indicates whether the trawl data were subjected to a test for outliers, in which outliers were eliminated.

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Methods